Echis coloratus, Giinther, in Africa. 423 



examples of E. coloratus are met with having- three rows of 

 such scales, a number occurring occasionally in E. carinatus, in 

 which, however, these scales are usually in two rows, whereas 

 in E. coloratus they are either in three or four. The enlarged 

 supraoculars generally present in the former species are 

 usually absent in the latter, and when present they are not 

 well developed. 



In the specimens of E. coloratus here tabulated the ventrals 

 range from 188 to 203, and the subcaudals from 46 to 51 ; 

 whereas in E. carinatus these shields vary, over the vast area 

 of its distribution, the ventrals from 132 to 194, and the 

 subcaudals from 23 to 48. So few examples of E. coloratus 

 are known, it is quite possible that the numbers of its ventrals 

 and consequently of its trunk- vertebrae may rise much higher 

 than the maximum number given above and also fall much 

 below the minimum of 188. The type of E. carinatus had 

 only 150 trunk-vertebras, whereas now, after more than a 

 century of research, individuals have been found with as few 

 as 132 and others with as many as 194 — that is to say, that 

 there may be as great a variation as 62 vertebras. This 

 result is obtained by the consideration of many individuals 

 from Asia and Africa brought together from between Madras 

 and West Africa ; but the vertebras in question may vary as 

 much as 39 among individuals from the same locality 

 (Deccan, India), whereas in others from Sind and from West 

 Africa the number of trunk- vertebrae may be practically the 

 same, viz. 143 and 145. The existence of this enormous 

 range of variation in the number of the vertebras of the indi- 

 viduals of this genus, even although it takes place in structures 

 which are mere repetitions the one of the other, is very 

 remarkable, because associated with it there is of necessity 

 a corresponding modification of the nervous and vascular 

 systems. With such variations occurring in the form of an 

 animal the possible modification of the epidermal structures 

 would seem to be almost limitless. The modus operandi by 

 which Nature effects these unstable variations of the skeleton 

 and soft tissues associated with it is an enigma unsolved by 

 any hypothesis as yet formulated. 



The coloration of these vipers from the Eastern Desert is 

 much the same as in the type, and as they have been quite 

 recently killed, its general character is better made out. 

 There are from 43 to 46 more or less transverse, narrow, pale 

 greyish areas, becoming almost light grey spots in the younger 

 specimen on the hinder part of the body. In both these pale 

 areas are margined with dark finely speckled grey, the inter- 



